Drinking rate, uptake of bacteria and microalgae in turbot larvae

The drinking rate of turbot larvae increased from 14 to 120 nl larva(-1) h( -1) from day 2 to 11 after hatching, which gave a slightly increased specif ic drinking rate (calculated per biomass) from day 2 to 7 (0.8-1.9 nl mu g carbon(-1) h(-1). The clearance rate of both algae and bacteria was 10-100 times higher than the drinking rate, which indicated that the larvae had an active uptake of both algae and bacteria. On day 2 and 4 after hatching hi ghest clearance rate was observed for Tetraselmis sp. On day 6 about the sa me clearance rate was observed for bacteria, Isochrysis galbana and Tetrase lmis sp. Until day 4 the turbot larvae had a higher ingestion rate of Tetra selmis sp. than of I. galbana. whereas on day 6 the rates were similar (28- 41 ng carbon larvae(-1) h(-1)). The assimilation efficiency was somewhat hi gher for I. galbana than for Tetraselmis sp., and on day 6 the assimilated algae constituted 1.5 and 0.9% of the larval biomass for I. galbana and Tet raselmis sp., respectively. (C) 1998 The Fisheries Society of the British I sles.